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Date:      Sun, 11 Feb 2024 12:19:37 -0800
From:      Mark Millard <marklmi@yahoo.com>
To:        Mario Marietto <marietto2008@gmail.com>
Cc:        freebsd-arm <freebsd-arm@freebsd.org>, freebsd-hackers <freebsd-hackers@freebsd.org>, FreeBSD Current <freebsd-current@freebsd.org>
Subject:   Re: How to use the L4 Microkernel with a FreeBSD userland.
Message-ID:  <440C30BB-5093-4ECB-94BE-21C73D461D0C@yahoo.com>
In-Reply-To: <ACAAF976-6868-4A88-99CB-5254CDE6C81C@yahoo.com>
References:  <CA%2B1FSijq0ez9%2BJXCSJP2rfWUXLjcTaEPJo-3NcO5Vu3H26L=hg@mail.gmail.com> <071E080E-C0E6-40F0-A0DF-4FCC22FC004D@yahoo.com> <CA%2B1FSign02NftThWsgVVRV6Ec83-T1sATiUKh7dHmmoXzW-_mg@mail.gmail.com> <ACAAF976-6868-4A88-99CB-5254CDE6C81C@yahoo.com>

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On Feb 11, 2024, at 12:00, Mark Millard <marklmi@yahoo.com> wrote:

> [Only replying to what I've subscribed to --and I dropped
> Warner as well.]
>=20
> On Feb 11, 2024, at 11:43, Mario Marietto <marietto2008@gmail.com> =
wrote:
>=20
>> ok. But what does this mean ? That I can use whatever Linux distro I =
want ? Or even the FreeBSD world ?
>=20
> Only to build L4Re.
>=20
> The LR4e built will not contain any Linux userland materials,
> nor any FreeBSD userland materials. LR4e has its own userland
> materials that will be present instead.
>=20
> http://os.inf.tu-dresden.de/download/snapshots/pre-built-images/arm64/
>=20
> already contains pre-built .elf and .uimage files Why not use one
> of those on the RPi4B?
>=20
> By size (larger), the most complete ones for the RPi4B seem to be
> (both formats):
>=20
> =
http://os.inf.tu-dresden.de/download/snapshots/pre-built-images/arm64/boot=
strap_vm-multi_rpi4.elf
> =
http://os.inf.tu-dresden.de/download/snapshots/pre-built-images/arm64/boot=
strap_vm-multi_rpi4.uimage
>=20
> =
http://os.inf.tu-dresden.de/download/snapshots/pre-built-images/arm64/boot=
strap_vm-basic_rpi4.elf
> =
http://os.inf.tu-dresden.de/download/snapshots/pre-built-images/arm64/boot=
strap_vm-basic_rpi4.uimage

May be you are wanting to run FreeBSD in a virtual machine
in the LR4e environment? For example,

http://os.inf.tu-dresden.de/L4Re/screens.html

shows a "Virtualized Linux running in a window" that is using
a virtual machine environment to run Linux in, not directly
using the Linux userland with the microkernel. It also shows
an example of "A vritual machine" that shows a GNU GRUB
running in the virtual machine.

For this the pre-built images should be sufficient: no need to
build your own L4Re. It is the virtual machine configuration
that would be then at issue.

>> On Sun, Feb 11, 2024 at 7:59=E2=80=AFPM Mark Millard =
<marklmi@yahoo.com> wrote:
>>=20
>>=20
>> On Feb 11, 2024, at 05:44, Mario Marietto <marietto2008@gmail.com> =
wrote:
>>=20
>>> I'm trying to understand how to use the L4 Microkernel with a =
FreeBSD userland. I've asked the same to a L4 developer,but he told me =
that he does not know FreeBSD,so I'm here to ask the same question. =
First of all I'm sure that it can be done,because it is written clearly =
on their website :
>>>=20
>>>=20
>>> http://os.inf.tu-dresden.de/L4Re/download/snapshots/
>>>=20
>>>=20
>>> on the section :
>>> Host system requirements
>>> The host system shall be a 64bit-based system with a recent Linux =
distribution installed and at least 2GB of free disk space.
>>> All necessary tools required by the build are available from the =
provided packages of the Linux distributions, including cross compilers. =
But there are also other cross compiler packages available (see below). =
You might want to run make check_build_tools in the src/l4 directory to =
verify the common tools are installed.
>>> You are free to use any Linux distribution you like, or even BSDs or =
any of its derivatives. But then you should know the game. Especially =
tool versions should be recent, as installed on the listed distributions =
below.
>>> We are confident that the snapshot works on the following =
distributions:
>>>    =E2=80=A2 Debian 11 or later
>>>    =E2=80=A2 Ubuntu 22.04 or later
>>>=20
>>> Let's say I want to use the L4 microkernel + FreeBSD 14 on my =
Raspberry Pi 4,the first step I did was to build L4Re for the =
Rpi,according with this instructions :
>>>=20
>>>=20
>>> http://os.inf.tu-dresden.de/L4Re/rpi.html=20
>>>=20
>>> This is the log file of the compilation,that hasn't given any  error =
:
>>>=20
>>>=20
>>> https://pastebin.ubuntu.com/p/6SwN2mpJBM/
>>>=20
>>>=20
>>> Or I could have taken a pre built image of the L4 microkernel here :=20=

>>>=20
>>>=20
>>> =
http://os.inf.tu-dresden.de/download/snapshots/pre-built-images/arm64/
>>>=20
>>>=20
>>>=20
>>> At this point the tutorial says that I should use a Linux distro. =
They suggest the official distro for the Raspberry Pi 4,that's RaspBian. =
But I don't want to use Linux as a userland,I want to use FreeBSD. The =
question now is : what should I do to achieve that goal ? How can I link =
the L4 microkernel with the ubldr bootloader of FreeBSD ? Or should I =
link it to the kernel of FreeBSD ? Can someone explain to me the missing =
step ? thanks.
>>=20
>> QUOTING the "Configuring yourself" section:
>> The make setup step configures predefined setups for both the L4Re =
microkernel (Fiasco) and the L4Re user-level software, and connects both =
together so the images for the target system can be built.
>> END QUOTE
>>=20
>> So L4Re has its own user-level software, not just a kernel. There is =
no use of a Linux or FreeBSD user-level software
>> when L4Re is booted. (They are just used for building.)
>>=20
>> "The host system" is just a host for building the L4Re parts and =
assembling the image from the parts. The "Pulling it together" section =
is about combining the parts (including the microkernel and the =
user-level software) to make the overall image that does not include =
Linux or FreeBSD code.



=3D=3D=3D
Mark Millard
marklmi at yahoo.com




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